The present disclosure relates to a prefilled syringe that stores a liquid drug prefilled in its syringe barrel and enables a user to recognize that the liquid drug has completely been discharged.
A prefilled syringe storing a liquid drug in its syringe barrel is used to administer the liquid drug into a subject person, such as a patient, to simplify preparation of the liquid drug for injection and to prevent the liquid drug for injection from being contaminated with bacteria. The prefilled syringe includes a syringe barrel storing a liquid drug. A gasket and a plunger are inserted in the syringe barrel. The gasket seals the syringe barrel in a liquid-tight manner to prevent leakage of the liquid drug, and the plunger slides the gasket. A pressing portion provided at the proximal end of the shaft portion of the plunger is pushed to slide the gasket in the syringe barrel. By the sliding of the gasket, the liquid drug is injected into the body of a subject person through an injection needle attached to the distal end of the syringe barrel.
WO 2013/046855 A discloses a prefilled syringe including a syringe barrel having a tapered liquid drug discharge portion provided on the distal end, an injection needle attached to and communicating with the liquid drug discharge portion, a gasket slidably housed in the syringe barrel, a plunger attached to the proximal surface of the gasket, a liquid drug stored between the gasket and the liquid drug discharge portion in the syringe barrel, an outer tube in which the syringe barrel and the plunger are inserted, a living body contact member that is slidably fit to the distal end of the outer tube and has a sleeve shape to house the injection needle, and a coil spring that urges the living body contact member toward the distal end in the outer tube. The prefilled syringe is used in such a manner that, by pressing the living body contact member onto the surface of a living body, the coil spring is compressed and the living body contact member slides in the outer tube to project the injection needle which then pierces the surface of the living body, such as a skin. Then by separating the living body contact member from the surface of the living body, the coil spring expands to house the injection needle again in the living body contact member.